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32kHz resonator with 12.5 pF - what will happen ?

Question asked by cols.matt on Oct 17, 2012
Latest reply on Oct 18, 2012 by knik
Due to an error in manufacturing we have a lot of modules with a 32khz resonator with 12.5 pF for low speed external clock and two 27pF aditional capacitor to ground.

Prozessor is the STM32F103RCT6. The real time clock unit is running half of time on a coin cell battery.

In the ST documentation it states "never use a resonator with a load capacitance of 12.5pF". Well .. seems like we have a problem. Also the clock seem to run at first tests.

Question: What happens due to this large load capacitance ? Does power consumption of the clock circuitry increase or does the clock runs wrong over time ?

Are there quick solutions ? - maybe taking of the additional 27pF capacitors ? Changing the resonator will be very hard to realize.

Thanks for your advise - Matt

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